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38 * @(#)buf.h 8.9 (Berkeley) 3/30/95
45 #include <sys/queue.h>
47 #include <sys/lockmgr.h>
55 * To avoid including <ufs/ffs/softdep.h>
57 LIST_HEAD(workhead, worklist);
59 * These are currently used only by the soft dependency code, hence
60 * are stored once in a global variable. If other subsystems wanted
61 * to use these hooks, a pointer to a set of bio_ops could be added
64 extern struct bio_ops {
65 void (*io_start) __P((struct buf *));
66 void (*io_complete) __P((struct buf *));
67 void (*io_deallocate) __P((struct buf *));
68 void (*io_movedeps) __P((struct buf *, struct buf *));
69 int (*io_countdeps) __P((struct buf *, int));
74 int (*bop_write) __P((struct buf *));
77 extern struct buf_ops buf_ops_bio;
80 * The buffer header describes an I/O operation in the kernel.
83 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
84 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
85 * originally requested buffer size and can serve as a bounds check
86 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
88 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
89 * ranges of dirty data that need to be written to backing store.
90 * The range is typically clipped at b_bcount ( not b_bufsize ).
92 * b_resid. Number of bytes remaining in I/O. After an I/O operation
93 * completes, b_resid is usually 0 indicating 100% success.
96 /* XXX: b_io must be the first element of struct buf for now /phk */
97 struct bio b_io; /* "Builtin" I/O request. */
98 #define b_bcount b_io.bio_bcount
99 #define b_blkno b_io.bio_blkno
100 #define b_caller1 b_io.bio_caller1
101 #define b_data b_io.bio_data
102 #define b_dev b_io.bio_dev
103 #define b_driver1 b_io.bio_driver1
104 #define b_driver2 b_io.bio_driver2
105 #define b_error b_io.bio_error
106 #define b_iocmd b_io.bio_cmd
107 #define b_ioflags b_io.bio_flags
108 #define b_pblkno b_io.bio_pblkno
109 #define b_resid b_io.bio_resid
110 struct buf_ops *b_op;
112 #define B_MAGIC_BIO 0x10b10b10
113 #define B_MAGIC_NFS 0x67238234
114 void (*b_iodone) __P((struct buf *));
115 off_t b_offset; /* Offset into file. */
116 LIST_ENTRY(buf) b_hash; /* Hash chain. */
117 TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
118 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
119 TAILQ_ENTRY(buf) b_act; /* Device driver queue when active. *new* */
120 long b_flags; /* B_* flags. */
121 unsigned short b_qindex; /* buffer queue index */
122 unsigned char b_xflags; /* extra flags */
123 struct lock b_lock; /* Buffer lock */
124 long b_bufsize; /* Allocated buffer size. */
125 long b_runningbufspace; /* when I/O is running, pipelining */
126 caddr_t b_kvabase; /* base kva for buffer */
127 int b_kvasize; /* size of kva for buffer */
128 daddr_t b_lblkno; /* Logical block number. */
129 struct vnode *b_vp; /* Device vnode. */
130 int b_dirtyoff; /* Offset in buffer of dirty region. */
131 int b_dirtyend; /* Offset of end of dirty region. */
132 struct ucred *b_rcred; /* Read credentials reference. */
133 struct ucred *b_wcred; /* Write credentials reference. */
134 void *b_saveaddr; /* Original b_addr for physio. */
140 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
141 TAILQ_ENTRY(buf) cluster_entry;
143 struct vm_page *b_pages[btoc(MAXPHYS)];
145 struct workhead b_dep; /* List of filesystem dependencies. */
148 #define b_spc b_pager.pg_spc
151 * These flags are kept in b_flags.
155 * B_ASYNC VOP calls on bp's are usually async whether or not
156 * B_ASYNC is set, but some subsystems, such as NFS, like
157 * to know what is best for the caller so they can
160 * B_PAGING Indicates that bp is being used by the paging system or
161 * some paging system and that the bp is not linked into
162 * the b_vp's clean/dirty linked lists or ref counts.
163 * Buffer vp reassignments are illegal in this case.
165 * B_CACHE This may only be set if the buffer is entirely valid.
166 * The situation where B_DELWRI is set and B_CACHE is
167 * clear MUST be committed to disk by getblk() so
168 * B_DELWRI can also be cleared. See the comments for
169 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
170 * the caller is expected to clear BIO_ERROR and B_INVAL,
171 * set BIO_READ, and initiate an I/O.
173 * The 'entire buffer' is defined to be the range from
174 * 0 through b_bcount.
176 * B_MALLOC Request that the buffer be allocated from the malloc
177 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
179 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
180 * by filesystems that allow clustering when the buffer
181 * is fully dirty and indicates that it may be clustered
182 * with other adjacent dirty buffers. Note the clustering
183 * may not be used with the stage 1 data write under NFS
184 * but may be used for the commit rpc portion.
186 * B_VMIO Indicates that the buffer is tied into an VM object.
187 * The buffer's data is always PAGE_SIZE aligned even
188 * if b_bufsize and b_bcount are not. ( b_bufsize is
189 * always at least DEV_BSIZE aligned, though ).
191 * B_DIRECT Hint that we should attempt to completely free
192 * the pages underlying the buffer. B_DIRECT is
193 * sticky until the buffer is released and typically
194 * only has an effect when B_RELBUF is also set.
197 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */
198 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
199 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
200 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
201 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
202 #define B_CACHE 0x00000020 /* Bread found us in the cache. */
203 #define B_VALIDSUSPWRT 0x00000040 /* Valid write during suspension. */
204 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
205 #define B_DONE 0x00000200 /* I/O completed. */
206 #define B_EINTR 0x00000400 /* I/O was interrupted */
207 #define B_00000800 0x00000800 /* Available flag. */
208 #define B_SCANNED 0x00001000 /* VOP_FSYNC funcs mark written bufs */
209 #define B_INVAL 0x00002000 /* Does not contain valid info. */
210 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
211 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */
212 #define B_MALLOC 0x00010000 /* malloced b_data */
213 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
214 #define B_PHYS 0x00040000 /* I/O to user memory. */
215 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */
216 #define B_DIRTY 0x00200000 /* Needs writing later. */
217 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */
218 #define B_WANT 0x00800000 /* Used by vm_pager.c */
219 #define B_WRITEINPROG 0x01000000 /* Write in progress. */
220 #define B_XXX 0x02000000 /* Debugging flag. */
221 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
222 #define B_08000000 0x08000000 /* Available flag. */
223 #define B_RAM 0x10000000 /* Read ahead mark (flag) */
224 #define B_VMIO 0x20000000 /* VMIO flag */
225 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
226 #define B_80000000 0x80000000 /* Available flag. */
228 #define PRINT_BUF_FLAGS "\20\40autochain\37cluster\36vmio\35ram\34ordered" \
229 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \
230 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \
231 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \
232 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age"
235 * These flags are kept in b_xflags.
237 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
238 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */
239 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */
240 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */
241 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */
243 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */
249 extern struct mtx buftimelock; /* Interlock on setting prio and timo */
250 extern char *buf_wmesg; /* Default buffer lock message */
251 #define BUF_WMESG "bufwait"
252 #include <sys/proc.h> /* XXX for curproc */
253 #include <sys/mutex.h>
258 #define BUF_LOCKINIT(bp) \
259 lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0)
262 * Get a lock sleeping non-interruptably until it becomes available.
264 static __inline int BUF_LOCK __P((struct buf *, int));
266 BUF_LOCK(struct buf *bp, int locktype)
271 mtx_lock(&buftimelock);
272 locktype |= LK_INTERLOCK;
273 bp->b_lock.lk_wmesg = buf_wmesg;
274 bp->b_lock.lk_prio = PRIBIO + 4;
275 bp->b_lock.lk_timo = 0;
276 ret = lockmgr(&(bp)->b_lock, locktype, &buftimelock, curproc);
281 * Get a lock sleeping with specified interruptably and timeout.
283 static __inline int BUF_TIMELOCK __P((struct buf *, int, char *, int, int));
285 BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int catch, int timo)
290 mtx_lock(&buftimelock);
291 locktype |= LK_INTERLOCK;
292 bp->b_lock.lk_wmesg = wmesg;
293 bp->b_lock.lk_prio = (PRIBIO + 4) | catch;
294 bp->b_lock.lk_timo = timo;
295 ret = lockmgr(&(bp)->b_lock, (locktype), &buftimelock, curproc);
300 * Release a lock. Only the acquiring process may free the lock unless
301 * it has been handed off to biodone.
303 static __inline void BUF_UNLOCK __P((struct buf *));
305 BUF_UNLOCK(struct buf *bp)
310 lockmgr(&(bp)->b_lock, LK_RELEASE, NULL, curproc);
315 * Free a buffer lock.
317 #define BUF_LOCKFREE(bp) \
319 if (BUF_REFCNT(bp) > 0) \
320 panic("free locked buf"); \
321 lockdestroy(&(bp)->b_lock); \
324 #ifdef _SYS_PROC_H_ /* Avoid #include <sys/proc.h> pollution */
326 * When initiating asynchronous I/O, change ownership of the lock to the
327 * kernel. Once done, the lock may legally released by biodone. The
328 * original owning process can no longer acquire it recursively, but must
329 * wait until the I/O is completed and the lock has been freed by biodone.
331 static __inline void BUF_KERNPROC __P((struct buf *));
333 BUF_KERNPROC(struct buf *bp)
335 struct proc *p = curproc;
337 if (p != PCPU_GET(idleproc) && bp->b_lock.lk_lockholder == p->p_pid)
339 bp->b_lock.lk_lockholder = LK_KERNPROC;
343 * Find out the number of references to a lock.
345 static __inline int BUF_REFCNT __P((struct buf *));
347 BUF_REFCNT(struct buf *bp)
352 ret = lockcount(&(bp)->b_lock);
359 struct buf_queue_head {
360 TAILQ_HEAD(buf_queue, buf) queue;
362 struct buf *insert_point;
363 struct buf *switch_point;
367 * This structure describes a clustered I/O. It is stored in the b_saveaddr
368 * field of the buffer on which I/O is done. At I/O completion, cluster
369 * callback uses the structure to parcel I/O's to individual buffers, and
370 * then free's this structure.
372 struct cluster_save {
373 long bs_bcount; /* Saved b_bcount. */
374 long bs_bufsize; /* Saved b_bufsize. */
375 void *bs_saveaddr; /* Saved b_addr. */
376 int bs_nchildren; /* Number of associated buffers. */
377 struct buf **bs_children; /* List of associated buffers. */
381 static __inline void bufq_init __P((struct buf_queue_head *head));
382 static __inline void bufq_insert_tail __P((struct buf_queue_head *head,
384 static __inline void bufq_remove __P((struct buf_queue_head *head,
386 static __inline struct buf *bufq_first __P((struct buf_queue_head *head));
389 bufq_init(struct buf_queue_head *head)
391 TAILQ_INIT(&head->queue);
392 head->last_pblkno = 0;
393 head->insert_point = NULL;
394 head->switch_point = NULL;
398 bufq_insert_tail(struct buf_queue_head *head, struct buf *bp)
400 if ((bp->b_ioflags & BIO_ORDERED) != 0) {
401 head->insert_point = bp;
402 head->switch_point = NULL;
404 TAILQ_INSERT_TAIL(&head->queue, bp, b_act);
408 bufq_remove(struct buf_queue_head *head, struct buf *bp)
410 if (bp == head->switch_point)
411 head->switch_point = TAILQ_NEXT(bp, b_act);
412 if (bp == head->insert_point) {
413 head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
414 if (head->insert_point == NULL)
415 head->last_pblkno = 0;
416 } else if (bp == TAILQ_FIRST(&head->queue))
417 head->last_pblkno = bp->b_pblkno;
418 TAILQ_REMOVE(&head->queue, bp, b_act);
419 if (TAILQ_FIRST(&head->queue) == head->switch_point)
420 head->switch_point = NULL;
423 static __inline struct buf *
424 bufq_first(struct buf_queue_head *head)
426 return (TAILQ_FIRST(&head->queue));
429 #define BUF_WRITE(bp) \
430 (bp)->b_op->bop_write(bp)
432 #define BUF_STRATEGY(bp) VOP_STRATEGY((bp)->b_vp, (bp))
435 buf_start(struct buf *bp)
438 (*bioops.io_start)(bp);
442 buf_complete(struct buf *bp)
444 if (bioops.io_complete)
445 (*bioops.io_complete)(bp);
449 buf_deallocate(struct buf *bp)
451 if (bioops.io_deallocate)
452 (*bioops.io_deallocate)(bp);
457 buf_movedeps(struct buf *bp, struct buf *bp2)
459 if (bioops.io_movedeps)
460 (*bioops.io_movedeps)(bp, bp2);
464 buf_countdeps(struct buf *bp, int i)
466 if (bioops.io_countdeps)
467 return ((*bioops.io_countdeps)(bp, i));
475 * Definitions for the buffer free lists.
477 #define BUFFER_QUEUES 6 /* number of free buffer queues */
479 #define QUEUE_NONE 0 /* on no queue */
480 #define QUEUE_LOCKED 1 /* locked buffers */
481 #define QUEUE_CLEAN 2 /* non-B_DELWRI buffers */
482 #define QUEUE_DIRTY 3 /* B_DELWRI buffers */
483 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
484 #define QUEUE_EMPTY 5 /* empty buffer headers */
487 * Zero out the buffer's data area.
489 #define clrbuf(bp) { \
490 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
494 /* Flags to low-level allocation routines. */
495 #define B_CLRBUF 0x01 /* Request allocated buffer be cleared. */
496 #define B_SYNC 0x02 /* Do all allocations synchronously. */
497 #define B_METAONLY 0x04 /* Return indirect block buffer. */
498 #define B_NOWAIT 0x08 /* do not sleep to await lock */
501 extern int nbuf; /* The number of buffer headers */
502 extern int runningbufspace;
503 extern int buf_maxio; /* nominal maximum I/O for buffer */
504 extern struct buf *buf; /* The buffer headers. */
505 extern char *buffers; /* The buffer contents. */
506 extern int bufpages; /* Number of memory pages in the buffer pool. */
507 extern struct buf *swbuf; /* Swap I/O buffer headers. */
508 extern int nswbuf; /* Number of swap I/O buffer headers. */
509 extern TAILQ_HEAD(swqueue, buf) bswlist;
510 extern TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
514 caddr_t bufhashinit __P((caddr_t));
515 void bufinit __P((void));
516 void bwillwrite __P((void));
517 int buf_dirty_count_severe __P((void));
518 void bremfree __P((struct buf *));
519 int bread __P((struct vnode *, daddr_t, int,
520 struct ucred *, struct buf **));
521 int breadn __P((struct vnode *, daddr_t, int, daddr_t *, int *, int,
522 struct ucred *, struct buf **));
523 int bwrite __P((struct buf *));
524 void bdwrite __P((struct buf *));
525 void bawrite __P((struct buf *));
526 void bdirty __P((struct buf *));
527 void bundirty __P((struct buf *));
528 int bowrite __P((struct buf *));
529 void brelse __P((struct buf *));
530 void bqrelse __P((struct buf *));
531 int vfs_bio_awrite __P((struct buf *));
532 struct buf * getpbuf __P((int *));
533 struct buf *incore __P((struct vnode *, daddr_t));
534 struct buf *gbincore __P((struct vnode *, daddr_t));
535 int inmem __P((struct vnode *, daddr_t));
536 struct buf *getblk __P((struct vnode *, daddr_t, int, int, int));
537 struct buf *geteblk __P((int));
538 int bufwait __P((struct buf *));
539 void bufdone __P((struct buf *));
540 void bufdonebio __P((struct bio *));
542 void cluster_callback __P((struct buf *));
543 int cluster_read __P((struct vnode *, u_quad_t, daddr_t, long,
544 struct ucred *, long, int, struct buf **));
545 int cluster_wbuild __P((struct vnode *, long, daddr_t, int));
546 void cluster_write __P((struct buf *, u_quad_t, int));
547 void vfs_bio_set_validclean __P((struct buf *, int base, int size));
548 void vfs_bio_clrbuf __P((struct buf *));
549 void vfs_busy_pages __P((struct buf *, int clear_modify));
550 void vfs_unbusy_pages __P((struct buf *));
551 void vwakeup __P((struct buf *));
552 void vmapbuf __P((struct buf *));
553 void vunmapbuf __P((struct buf *));
554 void relpbuf __P((struct buf *, int *));
555 void brelvp __P((struct buf *));
556 void bgetvp __P((struct vnode *, struct buf *));
557 void pbgetvp __P((struct vnode *, struct buf *));
558 void pbrelvp __P((struct buf *));
559 int allocbuf __P((struct buf *bp, int size));
560 void reassignbuf __P((struct buf *, struct vnode *));
561 void pbreassignbuf __P((struct buf *, struct vnode *));
562 struct buf *trypbuf __P((int *));
566 #endif /* !_SYS_BUF_H_ */